Concrete Extrusion Using Sustainable Cement Alternatives

The current research work aims to utilize materials as inert or pozzolanic additives to produce precast concrete elements in the extrusion process (3D concrete printing). This material is a residue with a mineral-silicate composition that has been processed using pneumatic flotation. It is a by-product of the extraction of valuable metals from dumps. For this purpose, the material has been comprehensively characterized mineralogically, chemically, and physically before processing. The present studies aim to determine requirements and restrictions for the appropriate preparation of the material. This material is intended as an additive for the partial substitution of cement in concrete mixtures without affecting the existing properties. The newly developed concrete mixtures were thoroughly examined as part of a material technology study. Limit states were determined in relation to the maximum dosage of the filler for existing concrete mixtures. As a result, the mechanical and physical properties were analyzed to ensure consistent strength requirements. The influence of the filling material on the time-dependent drying behavior and the strength development were examined in detail. By using the new concrete mixture in the extrusion process, its strengths in terms of sustainability are expanded. The innovative potential of the extrusion process in the construction industry offers significant opportunities for realizing more sustainable building structures. This is especially evident in the context of the production of precast concrete parts, where sustainability and the substitution of cement play a central role. The possibilities include improved material efficiency, increased design flexibility, and reduced environmental impact.